With increasing shortage of the conventional energy and deterioration of the environment on the earth, in the field of illumination, lighting devices with low power consumption and high environmental protection performance are more desired. LED (Light-Emitting Diode), as a light-emitting source, has characteristics of long lifespan, high brightness, low power consumption, no ultraviolet and infrared radiation, low heat generation, and so on. Since LED has notable effect in energy saving and can meet the current development demands of low-carbon, green and environmental protection, LED is widely used in the field of illumination, such as LED lighting, LED backlight, and the like.
As shown in FIG. 1, a conventional LED 11 comprises a LED support 6, a LED chip 1, electrodes 4, gold wires 2 and lead wires 3. In addition, the LED support 6 comprises an opaque housing 7, which is provided with a light-exiting window 5 allowing light emitted from the LED chip 1 to exit outwards. The LED chip 1 and the electrodes 4 are located inside the housing 7, and the LED chip 1 is connected to the electrodes by the gold wires 2. The lead wires 3 are provided outside the housing 7. The electrodes 4 inside the housing 7 are connected with the lead wires 3 outside the housing 7 so as to be connected to external circuits through the lead wires 3. Because the LED 11 emits light from a single side, light-emitting angle of the LED 11 is limited, which limits application of the LED 11. For example, in billboards lighting, home decoration, and other places, in order to enhance decorative effect, light-emitting angle should be enlarged, but the LED 11 emitting light from a single side cannot meet such need. In addition, light emitted from P/N junction region of the LED chip 1 in LED is non-directional. Single-sided light emission causes most light to be reflected and absorbed many times, thus light emission efficiency is reduced.
In the present market, double-sided light emission is realized usually by doubling the number of the single-sided LED(s) so as to place a single-sided LED in each of two directions. With such method, the number of used LEDs is increased, thereby the cost is increased. Moreover, in a LED lighting device manufactured by using such method, heat dissipation is adversely affected, and service life of the LED is reduced.